1. Field of the Invention
The present invention relates to a toilet bowl, and more particularly, to a hinge suitably usable for opening and closing a seat and seat lid of a toilet bowl.
2. Description of the Prior Art
Various types of hinges for opening and closing, or operating, a seat and seat lid of a toilet bowl have been proposed so far. Typical ones of such hinges include a combination of a shaft rotatable as the toilet seat and lid are pivoted for opening or closing, with a cam mechanism incorporating a compression spring and which acts on the shaft, a combination of a rotating shaft and a torsion spring which acts to cancel a torque of the shaft being rotated in a predetermined direction, a combination of a rotating shaft and a rotation damper, etc.
The combination of a rotating shaft with only a cam mechanism incorporating a compression spring and which acts on the shaft is advantageous in that a matching can easily be attained between a torque generated when the seat and lid is operated and an angular moment of the seat and lid. For a large rotating torque, however, the entire structure should be designed larger.
The combination of a rotating shaft with only a torsion spring which acts on the shaft has an advantage in that a small structure can create a large rotating torque. Since it creates a rotating torque which will increase and decrease linearly, however, no easy matching is possible between the rotating torque and an angular moment of the seat and lid which will depict a sine curve, and it is difficult to elaborately fit the movement of the seat and lid as necessary to the rotating torque and also to appropriately control the movement of the seat and lid in each of the operating steps.
Further, the combination of a rotating shaft with only a rotation damper has disadvantages that it is difficult to elaborately fit the movement of the seat and lid as necessary to the rotating torque and to appropriately control the movement of the seat and lid in each of the operating steps, and that the seat and lid being opened or closed cannot easily be halted in an intermediate angular position and braked at a predetermined angular position the seat and lid have reached during each of the operating strokes, for example.